Wiswesser line notation

Wiswesser Line Notation (WLN) is a chemical notation system used to represent the structure of chemical compounds using a linear string of characters. It was developed in the 1950s by William J. Wiswesser and has been utilized for various applications, including chemical database searches and information retrieval. While it has largely been superseded by other chemical notation systems such as SMILES and InChI, WLN remains an important part of the history of chemical informatics.

Overview

WLN is a method for encoding the molecular structure of chemical compounds in a compact, linear form. It uses a set of alphanumeric symbols to represent atoms, bonds, and other structural features. This allows for the efficient storage, searching, and retrieval of chemical information in databases. The notation is particularly notable for its ability to represent complex organic molecules in a relatively simple and straightforward manner.

History

Developed in the mid-20th century, WLN was one of the first attempts to create a standardized system for encoding chemical structures. Its development was motivated by the need for a more efficient way to store and search chemical information, which was becoming increasingly voluminous. Wiswesser's system gained significant adoption among chemists and information scientists for its simplicity and effectiveness.

Structure and Syntax

The structure of a WLN string is designed to reflect the molecular structure of the compound it represents. The notation uses letters to represent atoms, with certain letters indicating specific elements. Numbers and other symbols are used to denote bonding arrangements, ring structures, and functional groups. The syntax of WLN is rule-based, with specific guidelines for how to construct a notation string for any given molecule.

Applications

While WLN has been largely replaced by more modern chemical notation systems, it played a crucial role in the early development of chemical informatics. It was used extensively in chemical databases and information retrieval systems, facilitating the rapid search and identification of compounds. Additionally, WLN has been used in educational settings to teach the principles of chemical structure representation.

Comparison with Other Notation Systems

WLN is often compared to other chemical notation systems such as SMILES and InChI. While all these systems serve the same basic purpose of encoding chemical structures, they differ in their syntax, complexity, and the range of structures they can represent. SMILES and InChi, for example, are more flexible and can represent a wider variety of chemical structures, including inorganic compounds and complex organic molecules.

Legacy

Despite its decline in use, the Wiswesser Line Notation system remains an important part of the history of chemical informatics. It laid the groundwork for the development of more advanced chemical notation systems and demonstrated the feasibility and value of encoding chemical structures in a standardized, machine-readable format.

See Also

• Chemical nomenclature
• Chemical informatics
• Molecular modeling
• Computational chemistry